Bi(III) complexes of piroxicam and meloxicam: Synthesis, characterization, antioxidant, anti-inflammatory and DNA cleavage studies

Abstract

Piroxicam and meloxicam are therapeutically important compounds and their coordination complexes received immense importance in past few years. In present study, new Bi(III) complexes (1 and 2) of piroxicam (L1) and meloxicam (L2) were synthesized and characterized by spectral and physico-analytical techniques such as UV–Vis, FTIR, SEM-EDX, XRD and TGA. The spectral studies revealed that ligand L1 coordinated with the Bi metal in a bi-dentate manner through its amide oxygen (Oamide) and pyridyl ring nitrogen (Npyridyl) in complex 1. The ligand L2 coordinated through its amide oxygen (Oamide) and thiazolyl ring nitrogen (Nthiazolyl) in the complex 2. SEM and XRD results depicted different surface morphologies of both complexes. The different thermodynamic parameters (Ea, ΔS, ΔH and ΔG) were evaluated by using Coats–Redfern equation. Bio-efficacy of Bi(III) complexes (1 and 2) was evaluated by in-vitro and in-vivo methods, while, DNA cleavage was measured by gel electrophoresis technique. Furthermore, the binding interactions of both complexes with DNA was analysed by molecular docking. The results reveal that both the complexes have higher antioxidant potential and higher safety index up to 1000 mg/Kg (LD50) than free ligands. The complexes significantly inhibited carrageenan induced edema; 84 % inhibition by complex 1 and 71 % inhibition by complex 2. Furthermore, both the complexes have stronger tendency to cleave the DNA than the ligands. The Bi(III) complexes can further be explored in other inflammatory pathways to investigate their exact mechanism behind anti-inflammatory effect.